Repetition rate stabilization of the SBS Q-switched fiber laser by external injection

Repetition rate fluctuation is one of the main drawbacks of the low-threshold stimulated Brillouin scattering (SBS) Q-switched fiber laser. A method to stabilize the repetition rate is proposed in this paper by injecting a square-wave modulated light. It is measured experimentally that variance of the repetition rate can be improved from similar to 20% to similar to 1% of the period. It is also found that effectiveness of the method depends on modulation frequency and duty cycle of the injection. Its working mechanism is analyzed qualitatively. (C) 2009 Optical Society of America